The present invention relates to a vacuum deposition using pressurized reflow process, and more particularly to a method of forming a metal thin film on the substrate without producing any void in each recess.
It is known to form a metal thin film on a substrate having recesses using a sputtering method. An example of such a conventional metal thin film forming method is illustrated in FIGS. 1 to 3. As will be seen in FIG. 1, in case a thin film 1 of a metal material such as an alloy containing aluminium as a main composition is formed on a substrate 2 provided with a recess 3, a hollow 4 may be generated in the center region of the recess 3. In order to avoid the generation of such a hollow 4, the thin film 1 of the aluminium containing alloy formed on the substrate 2 is heated at temperature above approximately 500.degree. C. in case of Al based alloys so that it is melted. The melted metal of the thin film 1 may be drifted into the recess 3 so as to fill the recess 3 with the melted metal as shown in FIG. 2 and then may be cooled. It should be understood that the wording "melted" used herein is intended to include the conception of a softening or a fluidization.
However, in case the recess 3 provided on the substrate 2 is fine and has an aspect ratio of one or more, the melted metal can not be successfully drifted into the recess 3 and consequently a void 5 is left in the recess 3, which is surrounded by the metal of the thin film 1 as shown in FIG. 3.